Coupling



Feb. 29, 1944. G, v PICKWELL 2,343,079

COUPLING Filed Dec. 22, 1941 l lH//f Patented Feb. 29, 1944 UNITED STATES Parr-rrrv 'carica CGUPLING Glenn V. Pickwell, Dayton, Oli-io, assignor to Gen.

eral Motors Corporation, Detroit, Mich., a corporation of Delaware Application December 22, 1941, serial No. 423,950

2 Claims.

This invention relates to an improved machine element and the method of making it.

It is among the objects of the present invention to provide a husky torque absorbing coupling capable of being ,produced commercially without any appreciable variation in the characteristics of the numerous members produced.

A further object of the invention is to provide a torque absorbing coupling adapted operatively` to connect a power or drive shaft with a load or driven shaft and which is securely supported by said shafts, said coupling being adapted to transmit the rotative movement of the power shaft to the load shaft and to cushion and absorb any pulsations that may occur in the movement of V the power shaft, thereby preventing the pulsa-A tions from being transmitted to the load shaft..

These objects are accomplished by providing a coupling comprising rigid, collar-like mounting portions adapted to be secured to and sup-` airplanes with a fuel pump or booster pump,-` fracture of the shaft Willat times take place due to the pulsationsin the rotary movement provided bythe engine and transmitted through such shaft to the vfuel pump` orbooster which 4is y l acting upon a non-compressible element. the liq- To avoid such fractures, the driving c shaft of-'the engine. is connected toj the shaft -of the pumpV or bposter'bya yieldable coupling, usu-sally in the formel` a. coil-spring, sufciently heavy. to .transmit the'normal-driving power from the uidfuel.

engine shaftto-the pumpjshaft. Such springs are usually made by lwrapping a wire or metal bar about a mandrel then forming the. end convolu tions into eyelets by means ofwhich the spring may be attached to the respective elements to be connected.l To produce springs'commercially -and especially in large numbers .without lhaving anyl appreciable' variation in thel characteristics ofthe numerous'sprlngs is a very diiiicultprob.-

lemfand usually 'entails prohibitive 'scrap of materiali j y, A The present invention vprovides a husky torqueV absorbing coupling which maybemade in large numbers, one like the other without any appre-' ciable difference and entailing very little loss of material. A piece of` spring steel or tool steel seamless tubing of proper length, outlide and in- .side diameter may be used,or a rod of such ma terial may be bored out toprovide such a tubularmember. Then a spindle or core of a softer metal is secured in said tubular member. by soldering or any suitable way to secure the spindleagainst movement in the tubular member. -A spiral slot is then cut completely through the annular wall ofthe'tubular'member, after which the spindle is removed and the coupling then heat treated to the proper degree of hardness.' 'By providing stock 'material having the same specifications, all couplings made therefrom will be'substantially identical in characteristics for the operations to form the coupling have little or no effect upon the metallic structure ofthe material, excepting of course the heat treatmentl which, in all instances, is regulated to produce the proper degree piece.

Further objects and advantages ofthepresent. invention will be apparent from thefollowing description, reference being had to` the accom- .panying drawing wherein a preferredembodiment of the present invention' is clearly shown'. In the drawing:

Fig. l is an enlarged side view of the torque absorbing coupling.

rection of the arrow 2 of Fig. 1.

Fig. 3 is an end view of a shaft to which the.

` coupling may be secured and connected.

Fig. y4 is a sectional view showing the coupling secured between and connecting two shafts; l Referring to the drawing and particularly to Vfthe Figs. l and 2, the shock absorbing coupling 20 is illustrated as being a tubular member. It may be made of seamless tool-or spring steel .4 tubing or as described herein` byboringA out a. `rod ofthe same material.v Any number of heli' cal slots 2| are cut entirely through the annular wall of the tube the present drawing showing a double slot. The pitch and number ofthe slots y maybe varied'to produce couplings having desired characteristics. The respective ends of a 1 slot are diametrically opposite or substantially 180 apart and terminate short of thel respective ends vof the coupling. Thisprovides rigid, colof hardness4 in the finished.

Fig. 2 is an end view thereof taken in t'he'di` lar-like ends 2,2 'and 23, forming mounting por- Y tions by means ofwhichithe coupling may be sef 'curely anchored-tothe aligned adjacent ends ofv lili 'the driving anddriven shafts' to be connected.'Y

InFig.-4,the ydriving shaft is designated by the numeral 24 and the driven shaft by 2l.

The ends of the coupling are machined to provide longitudially extending tangs 2l of such a size and shape as to be adapted to nest in notches 2l of similar size machined in the circumferential surface of the driving and driven shafts 2l and 25.

In order to obtain smooth, balanced operation, it is desirable to so machine the ends of the coupling that the two tangs 26 at each end of the coupling are diametrically opposite and that their center is at approximately 90 to the ends of the two-slots as shown in Fig. l.

From the aforegoing it may clearly be seen that applicant has provided a torque absorbing coupling comprising rigid mounting collars each provided Iwith longitudinally` extending anchora ing tangs, said collars being secured together in spaced relation. by h'elically shaped elements integral withv said collars. Arranging the tangs 28,

which are the points of load application upon the coupling, at approximately' 90 relatively to the ends of the slots which form the helically shaped connecting elements and where the collar portion has its greatestarea, provides .for a balanced application-of the power upon the cantilever like connection between the helically shaped connecting elements and the rigid collars thereby substantiallyeliminating distortion due to the unbalanced aplication of forcesupon and through a yieldable element. The rigid collar portions providev for a/solid mounting of the coupling upon and between the two shafts to be Y operatively connected therefore eliminating undesirable and sometimes damaging whipping of the coupling especially at high speeds which will occur where ordinary springs are pivotally secured to studs onthe shafts passing through eyelets provided by the spring ends.

The process for producing a coupling as illustrated, which as shown in Fig. 4, drivingly connects, as for instance, an engine driven power shaft 24, journalled in the bearing |24 with an aligned, driven or fuel pump shaft 25 lournalled in bearing |25, comprises the following steps:

When tool steel or spring steel bar stock is used, measured lengths are centrally bored out to predetermined size. A softer metal core or spindle is then sweated or soldered in the bored out piece, after which the helical slot or slots are milled vor cut in any suitable way, the cut passing entirely through end into'the softer metal core whereby burrs Awithin the sleeve are substantially eliminated and a 'clean cut obtained. As hasbeensaid before, the two ends of a slot are dif netrically opposite ,or substantially 180 apart. After this slotting operation, the lpiece is normalized, thatv is, it is subjected to heat of approximately 1500 which relieves the hard steel sleeve of inherent strains,.the greater part of any :,ssaove distortion or twisting of the part due to the apheating of the sleeve also releases the core or spindle previously soldered therein and permits 5 its removal. Now theends of the coupling sleeve are machined to form the longitudinally extending mounting tangs which, as has been described are diametrically opposite at each end and arranged so that their center is substantially at 90 relatively to the ends of the slots. Following this the coupling sleeve is heat treated and drawn so as to have spring hardness which in usual practice is approximately 43-45 Rockwell C" degree. If necessary. interior and exterior grindl5 ing may be done to finish the piece. l

Notches of a size and shape similar to the size and shape of the tangs are cut in the annular surface at the shaft ends to be connected so that the tangs of the coupling may be securely nested therein.

With a supply stock of tool or spring steel rod or seamless tubing meeting specifications, this method of producing this particular shock or torque absorbing coupling sleeve substantially eliminates variations in the characteristics of the finished product and thereby absorbs iust the right amount of pulsating torque and transmits a uniform rotating torque without excessive vibration either in a rotating, an axial or a radial direction.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adoptedfall coming within the scope of the claims which follow.

What is claimed is as follows:

1. A torque absorbing coupling sleeve comprising a spring metal tubular member having a helical slot cut through its annular wall, the ends of the slot terminating at diametrically opposite sides, short of the ends of the said member so as to form rigid mounting portions; and tangs extending longitudinally'from the ends of the said member, the center of said tangs being angularly arranged at substantially relatively to the end 0f the helical slot.

2. A torque absorbing-coupling adapted to connect a variably rotating driving shaft with a load shaft comprising, a tubular member having tangs at each end adapted to interlock with corresponding -recesses in the driving and driven shafts so that said member is anchored to and supported by said shafts; and a helical slot through the annular wall volf-the member, the ends of said slot being substantially apart and terminating short of therespective ends of the tubular member, the center of the tangs being arranged at approximately 90 relatively to the slot ends.

GLENN vV. RICKWELL. 

